<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<script>
    {
        var a = 10;
        var b = 20;
        console.log(a);
        console.log(b);
    }


    //es6 增加新的定义变量语法，
    /*
    {
        let cc = 999;
        console.log(cc);
    }
    console.log(cc);
    */

</script>
</body>
</html>